Widespread population of invasive ferrets Mustela furo (Carnivora: Mustelidae) on the island of Madeira, Macaronesia

Invasive mammalian predators are arguably the most damaging group of alien animals for global biodiversity and their impacts are particularly damaging in endemic-rich insular ecosystems. Ferrets (Mustela furo) are well-known for their potential to establish self-sustaining feral populations. Yet, knowledge about their distribution and trophic interactions is scarce. Here, we provide ample evidence of a well-established and widespread population of ferrets on the subtropical island of Madeira (Portugal). Ferrets are using natural and human-dominated habitats, where they are preying on both native (e.g., Cory’s shearwaters (Calonectris borealis) and the endemic and IUCN Endangered Zino’s petrel (Pterodroma madeira)) and non-native vertebrates.